Refrigerant condensing unit



Nov.'19, 1957 T. M. ELFVING ET AL 2,813,405

I REFRIGERANT CONDENSING UNIT Fi led Sept. 29, 1955 2 Sheets- Sheet 1ill j w w w /w Wm M w; o 5 w W..[ A mz/ mam T. M. ELFVING ETAL 2,813,405

REFRIGERANT CONDENSING UNIT Nov. 19, 1957 Filed Sept. 29, 1953 2Sheets-Sheet 2 F'Lgore 3 United States Patent REFRIGERANT CONDENSINGUNIT Thore M. Elfving and Claes T. Elfving, San Mateo, Calif.

Application September 29, 1953, Serial No. 383,071

3 Claims. (Cl. 62117.8)

The present invention relates to refrigeration com pressors andparticularly to compressors of so-called hermetic or enclosed type, inwhich the compressor and its driving motor are contained in oneenclosure and the refrigerant becomes the atmosphere in which the motorruns. The gaseous refrigerant returning from the evaporator in thesuction pipe usually first enters the enclosure at the motor end. Intraveling through the motor, it first removes heat from the motorwinding and the motor metal and then passes to the compressor at theother end of the enclosure. The heat from motor and compressor absorbedby the refrigerant will eventually be removed with the other heatdissipated by the condenser.

The hermetic unit is not suitable for Wide variations in evaporatortemperatures. Motors and compressors are designed to obtain propercooling with a certain density of suction gas passing through theenclosure. A very considerable reduction in this density due to a largedrop in evaporator temperature will greatly decrease the cooling effectthat will be obtained. The result is inadequate cooling at evaporatingtemperatures materially below the design condition.

If the refrigerant gas in passing the motor winding becomes superheated,the power requirement per ton of refrigeration is increased.

It is an object of the invention to provide a refrigeration compressorin which adequate cooling of the motor-compressor unit is brought aboutregardless of the flow of refrigerant from the evaporator to thecompressor.

Other objects and advantages will be apparent from a study of thefollowing specifications taken in connection with the accompanyingdrawings wherein the invention is illustrated as adapted to a hermeticcompressor unit.

Although the invention is especially related to compressors of thehermetic type the principles of the invention can also be applied tocompressors of the open type.

In the drawings Figure 1 is a partly sectional end view of a hermeticcompressor unit having a condenser and built-in receiver.

Figure 2 is a partly sectional front view of the same unit.

Figure 3 is a top view of another type of hermetic compressor unithaving a condenser.

Figure 4 is a partly sectional view of the unit shown in Figure 3.

In Figure 1 and Figure 2 there is shown a hermetic motor-compressor unithaving an enclosure with a compressor housing at one end and a motorhousing 11 at the other end. The compressor 12 is of the piston type andhas splash or forced lubrication and a resulting heat transfer betweenthe piston and cylinder zone and the lower portion of the crankcase. Italso has a discharge valve 13 from which a pipe 14 takes the refrigerantto a condenser 15, air cooled by means of a fan 16. From the condenser15 a relatively large pipe 17 leads the liquid refrigerant downwardly toa receiver 18. According to the invention, the receiver to a largeextent 2,813,405 Patented Nov. 19, 1957 surrounds the lower part of themotor-compressor unit so that the motor housing 11 and the lower part ofthe compressor housing 10 with the crankcase sump are in effectsubmerged in liquid refrigerant and consequently are in good heattransferring relationship therewith. From near the bottom of thereceiver a pipe 19 carries liquid refrigerant through a heat exchanger20 and from there to an expansion valve (not shown) and evaporator (notshown) in the usual Way. The return from the evaporator goes to theouter jacket of the heat exchanger from which a suction pipe 21 carriesrefrigerant gas back to the hermetic unit through an intake valve 22.

By the arrangement according to the invention, the motor-compressorenclosure will be efliciently cooled by refrigerant in the surroundingreceiver 18. Heat given off through the motor-compressor housing to theliquid refrigerant in the receiver evaporates a corresponding amount ofrefrigerant. The formed vapor rises and enters the condenser 15 throughthe large pipe 17 and condenses. The pipe 17 is large enough so thatthere: can readily be a simultaneous flow of refrigerant gas passingfrom the receiver to the condenser in counterflow to the liquidrefrigerant going from the condenser to the receiver. The pipe 17 andthe condenser pipes 15 should therefore be pitched downwardly and be ofliberal diameter so that gas will be allowed to rise from the receiverback into the condenser.

In case a small pipe condenser is used, or if the condenser or the pipe17 is formed or installed to make liquid pockets, a separaterecirculating cooling system may, according to the invention, be used.This separate recirculating cooling system comprises a heat dissipatingpart 23 in the form of a condenser coil located above the liquid surfacein the receiver 18 and connected by a pipe 24 with the upper part of thereceiver 31$, which forms the heat'absorbing part of the system. Thepipe 24 and the condenser 23 preferably have an inner diameter of atleast /2 with the connections made in such a way that all parts of thesystem are Well drained to the receiver. The cooling of themotor-compressor housing will take place by the evaporation ofrefrigerant in the receiver 18, the vapor rising into the coil 23 Thevapor then condenses in the condenser coil 23 and as liquid will flowback to the receiver.

The receiver and thereby also the m'otor'compressor housing will,according to the invention, maintain a temperature only slightly higherthan that of the coil 23. The auxiliary coil 23 should be located infront of the main or proper condenser 15 and is also provided with fins25. The cooling coil 23 will be cooled to a temperature of the condenser15 and the hermetic motor-compressor unit will therefore be efiicientlycooled during any working condition independent of the density of thesuction gas. In order to maintain good heat transfer conditions thecondenser coil 23 should be provided With a valve 26 for elimination ofair or other non-condensable gases.

Figures 3 and 4 show another embodiment of the invention. A hermeticcompressor 30 has a motor housing 31 located eccentrically above acompressor housing 32. A motor 33 drives a vertical shaft 34 providedwith a hollow center 35, through which oil is pumped by an oil pump 36at the lower end of the shaft below the oil level in the compressorhousing. A compressor 37 with two horizontal cylinders 38 and 39 isdriven by the vertioal shaft. At the top of the cylinders a valvechamber 40 is disposed and to which a suction line 41 and a dischargepipe 42 are connected. The discharge pipe 42 is connected with acondenser 43, air cooled by a fan 44. From the condenser 43 the liquidrefrigerant is carried by a pipe as to a receiver at, which is builtaround the lower part of the compressor housing 32, so that the oil sumpis in good heat transfer relationship with and in effect is submerged inliquid refrigerant. From the bottom of the receiver 46 a pipe 47 carriesliquid refrigerant to an evaporator (not shown) preferably through aheat exchanger in the usual Way.

The receiver and the oil sump and the whole rnotorcompressor unit arecooled by a recirculation system using the refrigerant of the system asheat transfer medium. A heat dissipating part 48 or auxiliary condenseris located above the refrigerant liquid level in the receiver 46 and isconnected therewith by a large, inclined pipe 49. The heat dissipatingpart, according to the invention, preferably includes a comparativelylarge condenser tube or coil provided with fins St for effective coolingby the air blown by the condenser fan 4 An air valve 51 is provided atthe highest point of the coil for release of air in purging.

Heat from the oil sump is absorbed upon evaporation of a correspondingamount of refrigerant in the receiver 46. The refrigerant gases maypartly reenter the lower portion of the condenser 43 but mainly passthrough the pipe 49 to the heat dissipating part 48 of the coolingsystem. Therein condensation takes place at a temperature determinedmainly by the temperature of the air and the heat transfer capacity ofthe heat dissipating part 48 in relation to the heat developed in themotor-compressor housing. The motor-compressor unit will in this Way beefficiently cooled Without outside air cooling, which in many places isdifficult to arrange. By the invention it is no longer necessary toexpose the hermetic compressor unit to outside forced air cooling andthe condenser and the condenser fan do not have to be located in frontof the compressor for passage of air over the motor-compressor housing.

In the described embodiments of the invention, the heat absorbing partof the cooling system serves as receiver for the condensing unit. it is,according to the invention, possible to arrange a separate heatabsorbing part in heat transferring connection with the motorcompresso-rhousing and with liquid communication with the condensereceiver systemfor the passage of liquid refrigerant to the heat absorbing part of thecooling sys tem without having the heat absorbing part serving asreceiver. The heat absorbing part of the refrigerant recirculationsystem, according to the invention, may also consist of liquid pipes orcoils located below the oil level inside the sump of the compressor orlocated in thermal contact with any part of the motor-compressor system,where cooling is desirable.

While several more or less specific embodiments of the invention havebeen shown, it is to be understood that this is for the purpose ofillustration only, and that the invention is not to be limited thereby,but its scope is to be determined by the appended claims.

What is claimed and is to be secured by Letters Patent 1s:

1. A refrigeration compressor comprising a driving motor, a compressorconnected thereto, a housing for said driving motor and said compressorhaving a heat transferring wall, a jacket enclosing at least part ofsaid wall and forming a receiver for gaseous and liquid refrigerant, acondenser disposed above said receiver, means for carrying gaseousrefrigerant from said compressor to said condenser, and a relativelylarge connecting pipe extending between the bottom of said condenser andsaid receiver above the liquid refrigerant therein, said pipe being of asize to conduct gaseous and liquid refrigerant simultaneously inopposite directions.

2. A refrigeration compressor comprising a driving motor, a compressorconnected thereto, a housing for said driving motor and said compressorhaving a heat transferring wall, means including said wall forming areceiver for gaseous and liquid refrigerant, a condenser located in theatmosphere and disposed entirely above said liquid refrigerant in saidreceiver, means for circulating refrigerant from said receiver throughsaid compressor and into said condenser, and a single pipe for freelyconducting gaseous and liquid refrigerant simultaneously in bothdirections between said condenser and said receiver.

3. A refrigeration compressor comprising a driving motor, a compressorconnected thereto, a housing for said driving motor and said compressorhaving a heat transferring wall, means including said wall forming areceiver for gaseous and liquid refrigerant, a condenser located in theatmosphere and disposed entirely above said liquid refrigerant in saidreceiver, means for circulating refrigerant from said receiver throughsaid compressor and said condenser, means for draining liquidrefrigerant from said condenser to said receiver, and means forconducting ascending gaseous refrigerant from said receiver directly tothe bottom of said condenser, and in which said draining means and saidconducting means include a pipe of a size to conduct gaseous and liquidrefrigerant simultaneously in opposite directions and inclineddownwardly from the bottom of said condenser to said receiver above theliquid refrigerant therein.

References Cited in the file of this patent UNITED STATES PATENTS1,284,964 Anderson Nov. 19, 1918 1,313,363 Williams Aug. 19, 19191,509,998 Geiger et a1 Sept. 30, 1924 2,051,110 Smith Aug. 18, 19362,146,484 Philipp Feb. 7, 1939 2,300,005 Philipp Oct. 27, 1942 2,417,582Barfield Mar. 18, 1947 2,478,137 Timmer Aug. 2, 1949 2,496,143 BackstromJ an. 31, 1950 2,672,736 Philipp Mar. 23, 1954

